I Had My Eyes Checked By An Optometrist In Sep

I had my eyes checked by an optometrist in Sep 2015 and got a new pair of glasses. However, recently I have been having difficulty in reading things on the computer screen as well as paper, both with my new bifocals as well as dedicated reading glasses. Yesterday I went to the same optometrist and got my eyes tested again and learnt that the powers have significantly increased in the last 8 months. Anything else I should be worried about or should do other than just getting my new prescription filled? I do suffer from dry eyes in the night (is that called "nocturnal lagophthalomos" - you can blame the Internet for that)